The present invention relates generally to apparatus for cutting successive, measured, longitudinal sections from an elongated filamentary workpiece having a core surrounded by one or more layers of a coating material, cutting at least partially through the coating layer(s) at selected distances from one or both ends of each section to permit severing of a slug of the coating material from the main body thereof and optionally either partly or fully removing the slug(s) of coating material to expose portions of the core. More specifically, the invention relates to novel and improved features of such apparatus, notably including a single pair of blades which serve both to cut entirely through the filamentary member and to cut only through the coating material, as well as features of the apparatus for guiding and moving the workpiece.
Apparatus of the type described in the preceding paragraph is widely used in the electrical and electronics industries to supply high volumes of precut lengths of wire or cable, often with a portion of the insulating or other coating layers removed at one or both ends of each section. As the wire or other elongated member to be processed is fed longitudinally through the apparatus, microprocessor based drive means operate cutter blades to sever the wire into sections of preselected or "measured" lengths, to cut at least partly through the insulation and to sever and strip a slug of insulation from the end of the wire by moving the wire section longitudinally while the blades are engaged with the insulation. Such apparatus has become known in the industry as measure-cut-strip machines. Although such apparatus may be used to process coated optical fiber or other elongated, filamentary materials of uniform cross section having a central core surrounded by one or more layer(s) of covering material(s), for purposes of discussion and illustration herein the workpiece or material to be processed will be considered a simple electrical wire comprised of a conductor coated with a layer of plastic insulation.
Cutting the wire into separate sections, and cutting through the insulation prior to stripping s slug from the conductor, is performed in most of the current measure-cut-strip machines by two or more pairs of blades having opposed cutting edges. For example, the measure-cut-strip machine of related U.S. Pat. Nos. 5,146,673, 5,253,555 and 5,265,502 employs three pairs of blades, a center pair for cutting through the entire wire, with additional blade pairs on each side for cutting through and stripping the insulation. Although this adds to the cost and complexity of the machine by requiring separate elements for mounting and moving each set of blades, it has been found that using the same set of blades to cut the wire and to cut and strip the insulation can produce poor results; e.g., the blade edges may become nicked after repeatedly cutting through the wire or cable, causing uneven cutting and/or stripping of the insulation.
One of the objects of the present invention is to provide a measure-cut-strip wire processing machine utilizing only one pair of blades while avoiding problems inherent in cutting the wire with the same cutting edges used to cut and strip the insulation. Another, related object is to provide measure-cut-strip wire processing apparatus having highly accurate, yet simple and relatively inexpensive mechanism for supporting and moving the blades which cut the wire and cut and strip the insulation.
The wire is moved axially in forward and rear directions through the machine of the aforementioned patents by a pair of conveyors, one forwardly and one rearwardly of the three pairs of blades, each comprising a pair of endless belts passing around spaced wheels or rollers and having opposed, elongated stretches for engaging opposite sides of the wire. While such conveyor means are, in general, advantageous for moving the wire axially as it is processed, there are also certain disadvantages. It is a further object of the present invention to provide improvements in conveyor-type wire transporting means in measure-cut-strip wire processing apparatus.
In generally, the objects of the invention are to provide novel and improved wire processing apparatus of the measure-cut-strip type having highly efficient and accurate operating features coupled with simple and economical construction requiring a minimal member of parts, and to provide novel and improved blade means for use in such apparatus.